Non-invasive automatic glucose sensor system

ABSTRACT

A unique glucose sensor to determine the glucose level in patients, for example, for use in treating or diagnosing diabetes. The patient&#39;s eye is automatically scanned using a source of radiation at one side of the patient&#39;s cornea. A sensor located at the other side of the cornea detects the radiation that passed through the cornea. The level of glucose in the bloodstream of the patient is a function of the amount of radiation detected at the other side of the cornea of the patient. The result is transmitted to a remote receiver that is coupled to a readout device to thereby provide non-invasive glucose determinations.

This invention relates to diagnostic and/or curative instrumentsutilized by modern medicine and more particularly, to non-invasiveautomatic glucose sensing systems.

At the present, to determine the amount of glucose in the patient'ssystem for thereby determining whether or not the patient has diabetesor has need of insulin, urine or blood specimens are examined. It iswell known that the glucose level varies in people. It is especiallyimportant to know what the glucose level is in people afflicted withdiabetes. In diabetics the level often reaches the point where it isnecessary to provide the patient with insulin.

The present method of detecting and treating diabetic patients is forthe patient to provide the hospital, doctor or lab technician with thespecimens of urine and/or blood which are analyzed. If diabetes is thenfound, insulin is prescribed. Since the glucose level in each individualis variable, the amount of insulin which the patient takes does notnecessarily correlate to the average glucose level. Nonetheless, thereis no present method of reliably indicating to the patient that it isnecessary for him to take insulin at a certain time or for readilydetermining the glucose level in the patient's blood. Thus, manypatients do not take the necessary insulin when they really need it withthe consequent adverse effects. Alternatively, many patients take moreinsulin than they need and suffer from hypoglycemia.

Thus, the present systems are inadequate because, among other things,they only give instantaneous readings. Further, the blood sample methodrequires puncturing the skin with a hypodermic device which isinconvenient, time consuming and bothersome. Further, as pointed out,the blood sugar varies widely with variables in the daily routine suchas acute illness, diet, physical exercise, etc. This means, that theroutine insulin dose may be totally incorrect for a day that is notroutine.

Accordingly, an object of the present invention is to provide aconvenient way of continuously monitoring the control of glucose levelin diabetics.

A further object of the present invenion is to provide sensitive,non-invasive glucose sensors which can diagnose new cases of diabetes.

Yet another object of the present invention is to provide glucosesensing devices that give an automatic readout showing how much glucoseis present so that a person with a minimum of training, such as thepatient himself, or a simple computer can reliably determine thediabetic control, and therefore, know whether or not to administerinsulin.

In accordance with a preferred embodiment of the invention a softscleral contact lens shaped to fit over the cornea is provided with abuilt-in energy wave transmitter, such as an infrared source on one sidethereof and an infrared detector on the other side. A power source isalso mounted in the soft scleral contact lens. The infrared source isaimed to cause the infrared radiation to pass through the cornea and theaqueous humor to the infrared detector. A transmitter is mountedadjacent to the detector and coupled thereto for transmitting a signalthat is a function of the infrared level detected. A remote receiverfunctions to receive the signal transmitted and couple that signal to areadout device which automatically provides a readout determinative ofthe glucose content in the aqueous humor which is directly proportionalto the glucose content of the blood. Switching means may be provided toactivate the system.

These and other objects and features of the invention will now beexplained with the aid of the accompanying drawings, in which:

FIG. 1 is a front view of the patient's eyeball having a contact lensthereon which is equipped with the glucose sensor system;

FIG. 2 is a side view of the eyeball of FIG. 1 having the lens thereonwith the non-invasive glucose sensor system mounted thereto; and

FIG. 3 is a block diagram showing of a receiving system providing areadout of the glucose content as determined by the non-invasive sensorsystem.

As shown in FIG. 1 the eye, generally shown as 11, is equipped with anon-invasive glucose sensor system, generally shown as 12. The glucosesensor system is mounted into a contact lens 13. The contact lens ispreferably a soft scleral contact lens. The lens fits over part of thecornea and part of the sclera 27, covering the iris 14.

As can be seen particularly, in FIG. 2, the cornea covering the iris 14and the pupil 15 resembles a mound in that it has a different radius ofcurvature and, therefore, rises above the level of the rest of theeyeball. The non-invasive glucose sensor system is shown mounted at theperiphery of the iris. Radiation source means are provided. For example,an infrared source 16 is shown mounted in the contact lens at one sideof the iris. It emits an infrared radiation shown at 17, which isreceived by the infrared radiation detector 18. The amount of radiationreceived by the infrared radiation detector 18 is a function of theamount of glucose in the patient's blood.

Also, shown is a power source 19 mounted in the contact lens which maybe any well known small nickel cadmium battery, for example, coupled tothe infrared source 16 to provide it with the necessary power. Thebattery is shown coupled to the detector through conductor 21.

One preferrable source of infrared radiation is a zirconium filamentlight bulb emitting a ray having a wave length of 0.975 microns. Thedetector used may be a thermistor bolometer. It should be understoodthat other radiation emitting and detecting devices are within the scopeof this invention. For example, visible light may be similarly directedand detected by an interferometer which will measure the change inrefractive index produced by the glucose content in the aqueous humor.

The detector 18 is shown at the other side of the iris, mounted in thesoft scleral lens. The detected infrared radiation is a function of thesugar content because the hydroxyl in glucose affects the infraredradiation, thereby changing the amount of infrared detected by detector18.

Means are provided for transmitting the detector output. Moreparticularly, transmitter 22 sends the detected signal that is receivedat receiver 23. The signal from receiver is amplified at amplifier 24which is connected to a readout device 26. The readout device ispreferably a direct digital readout device. This receiver and readoutdevice are only shown in block diagram form, since many different modesof receiver and readout can be used.

Most cases of diabetes cannot be cured, but almost all may be controlledby injections of insulin and careful attention to diet. The diabeticlearns to test his urine for sugar and to give himself injections ofinsulin to augment the failure of the pancreas to produce enough of thathormone.

In practice the patient slips the soft scleral contact lens over his eyeand automatically, with no appreciable impairment to his vision, theglucose system is in position to transmit a signal that is a function ofthe glucose content in blood. He may either carry the receiving andreadout device, as shown in FIG. 3, or may utilize it in his home. Thepatient is able to determine from the readout device whether or not heneeds to inject more insulin or alter his diet.

A switching arrangement is indicated at 31 and 32. The switches 31 and32 in series between the power source and the source 16 and the detector18 are micro switch varieties which are operated by pressure applied,such as through the closure of the patient's eyelids to start and stopthe system. Alternatively, the switching devices 31 and 32 could operateon a time basis or on a start signal basis. For example, the glucosesensor can be programmed to readout either on a time basis -- once everyhour -- or else upon receiving a signal from a start transmitter (notshown) carried by the patient, and then run for a specific time period.

While the principles of the invention have been described above inconnection with specific apparatus and applications, it is to beunderstood that this description is made only by way of example, and notas a limitation on the scope of the invention. For example, since thebody in general, and in particular, the iris at 98.6° F is, in itself, asource of infrared radiation at low amplitude, it may be possible, afterfurther improvement in the sensitivity of the detector, to eliminate theartificial infrared source entirely. Again, as better detectors aredeveloped, it may be also possible to employ other types of radiationthan infrared.

I claim:
 1. A non-invasive glucose sensor system for determining the sugar content in the user's blood,said system comprising radiation source means for emitting radiation of certain wave lengths, said certain wave lengths being altered by sugar derivatives, radiation detecting means for detecting said certain wave lengths, power source means for providing power to said radiation source means and said radiation detecting means, mounting means for mounting said radiation emitting means and radiation detecting means spaced apart from each other, but in line with each other, so that the radiation detecting means receives the certain wave lengths of the radiation source means, the distance said radiation source means and said radiation detecting means are spaced apart being at least equal to the diameter of the cornea of the human eye, said mounting means being adapted to be fitted contiguous to a user's eye with said radiation source means and radiation detecting means at opposite sides of the cornea of the human eye so that said radiation of said certain wave lengths passes through the cornea of the user's eye in going to the radiation detecting means, and said radiation detecting means comprising indicator means for indicating the sugar content of the user's blood as a function of the detected radiation.
 2. The non-invasive glucose sensor system of claim 1 wherein said means for mounting said radiation emitting means and said radiation detecting means comprises contact lens means.
 3. The non-invasive glucose sensor system of claim 2 wherein said contact lens means is a soft scleral contact lens.
 4. The non-invasive glucose sensor system of claim 2 wherein said radiation emitting means is mounted in the contact lens substantially at that portion of the contact lens that is at the periphery of the user's iris, and wherein said detector means is mounted opposite to said emitter means on the contact lens at the periphery of the user's iris, when the sensor is in use.
 5. The non-invasive glucose sensor system of claim 1 wherein said radiation emitting means comprises means for emitting infrared radiation, and wherein said detecting means comprises means for detecting infrared radiation.
 6. The non-invasive glucose sensor system of claim 1 wherein means are provided for transmitting a signal that is a function of the detected radiation obtained from said radiation detector means and receiving means for receiving said transmitted signal to provide an indication of the glucose content of the user's blood.
 7. The non-invasive glucose sensor system of claim 6 wherein said receiving means includes digital readout means for digitally providing a readout determinative of the glucose content of the user's blood.
 8. The non-invasive glucose sensor system of claim 7 wherein switching means are provided for selectively actuating said system.
 9. The non-invasive glucose sensor system of claim 8 wherein said switching means comprises pressure sensitive switches which are actuated by the user through his eyelids.
 10. A method of obtaining a direct reading of sugar content of a person non-invasively and automaticaly, said method comprising the steps of: transmitting radiation rays through the cornea of the patient's eye; detecting radiation rays which have passed through the cornea of the patient's eye; translating the detected radiation rays to obtain a readout indicative of the sugar content in the patient's blood.
 11. The method of claim 10 including the steps of transmitting a signal that is a function of the detected radiation, receiving the detected signal and translating the received, detected signal into a digital readout indicative of the sugar content of the person's blood.
 12. The method of claim 11 including the step of mounting said transmitting means and said detecting means, as well as transmitter means onto a contact lens and placing the contact lens in the patient's eye, and then selectively actuating the radiation emitting means, the radiation detecting means and the transmitting means. 